A third baby has died and at least 6,244 are sick after consuming contaminated milk powder, Chinese health officials said today (17 September).

A spate of cases of infants with kidney stones had first been linked to Sanlu Group's milk formula, which was found to be contaminated with the industrial chemical melamine.

However, inspections on samples from more than 100 producers have found a further 21 companies were selling contaminated products, including Beijing Olympics sponsor Yili and leading dairy Mengniu. These products are now being recalled, said the State Administration for Industry and Commerce on its website.

Two of the firms had exported milk powder to five countries in Asia and Africa, according to China's quality watchdog AQSIQ.

The government has also sacked four officials in Hebei province where Sanlu is based. They include the vice mayor in charge of agriculture and the director of the city's food and drug watchdog. Sanlu general manager and chairwoman Tian Wenhua has also been dismissed.

Meanwhile, Fonterra has recalled one batch of milk for pregnant women sold in China under the Anmum Materna brand name. A statement said the batch, distributed only in China, was manufactured under licence by Sanlu using "what we believe to be contaminated local raw milk".

All other Anmum and Anlene products in the market have been produced using only imported milk from New Zealand and adhere to the strictest standards, it said.